This application relates to improved complex tolylene polyurea-thickened grease compositions containing less than 7 parts per million 2,4-diaminotoluene. The application also relates to a process for making complex tolylene polyurea-thickened grease compositions containing less than parts per million 2,4-diaminotoluene wherein an anhydride is one of the reactants.
Polyurea-thickened greases are well known in the art. See, for example, U.S. Pat. Nos. 3,242,210 and 3,243,372, the entire disclosures of which are incorporated herein by reference.
In the past alkaline earth metal carboxylates and alkaline earth metal carbonates have been utilized with polyurea-thickened greases as taught in U.S. Pat. Nos. 3,846,314 and 3,920,571. Polyurea-thickened greases containing these alkaline earth metal additives are known as complex polyurea-thickened greases.
It has been found that complex tolylene polyurea-thickened greases contain significant amounts of 2,4-diaminotoluene, generally averaging greater than 8 ppm and frequently in the range of 20 to 200 ppm or more. It has furthermore been found that 2,4-diaminotoluene causes cancer in laboratory animals.
Japan Kokai Pat. SHO 59-199797 (1984) discloses the use of an anhydride in the preparation of a lithium soap grease with a high drop point. This patent teaches a method of using acetyl chloride or acetic anhydride to react with the hydroxyl groups in the lithium soap grease to improve flow properties of the grease.
One object of the present invention is to produce a complex tolylene polyurea-thickened grease containing essentially no detectable 2,4-diaminotoluene.
Other objects will be readily apparent to those skilled in the art from a reading of this specification.